In the field of semiconductor manufacturing, it has been recognized since the beginning of the industry that maintaining the semiconductor wafers free of contaminants during the manufacturing process is a critical requirement to producing quality profitable wafers. As the size of the devices continue to become smaller, the number of semiconductor devices present on a single wafer continues to exponentially grow. As a result of the devices becoming more and more miniaturized, cleanliness requirements have also become increasingly important and stringent. When dealing with reduced size devices, the ratio of the size of a contaminant compared to the size of a device is greater, resulting in an increased likelihood that a contaminated device will not function properly. Thus, increasingly stringent cleanliness and PRE requirements are needed. As a result, improved semiconductor wafer processing techniques that reduce the amount and size of the contaminants present during wafer production are highly desired.
An example of a single-wafer cleaning system that utilizes megasonic energy is disclosed in U.S. Pat. No. 6,039,059 (“Bran”), issued Mar. 21, 2000. An example of a single-wafer cleaner and dryer is disclosed in U.S. Pat. No. 7,100,304 (“Lauerhaas et al.”), issued Sep. 5, 2006. The entireties of Bran and Lauerhaas et al. are hereby incorporated by reference.
In single-wafer processing systems, such as the ones mentioned above, a semiconductor wafer is supported and rotated in a horizontal orientation. A desired processing chemical is then applied to one or both sides/surfaces of the wafer. Nozzles/dispensers are typically placed underneath the wafer and dispense fluid in an upward direction so as to apply the fluid on the bottom surface of the wafer. It is important that the level of contaminants and/or residues left on the surface of the wafer be minimized to the extent possible at all times.
While the dispensers serve the vital function of applying fluids to the surface of the wafer, they also present a problem in that fluid and contaminants will collect on the top surface of the dispenser and get re-deposited back on the wafer. Thereby re-contaminating the wafer and causing semiconductor device failure problems. Additionally, because the wafer spins during the application of fluid, turbulence is created between the bottom surface of the wafer and the top surface of the dispenser that may damage the wafer or may cause more contaminants to remain on the surface of the wafer.
Therefore, there is a need to provide an improved apparatus, system and method for processing substrates that prevents and/or minimizes the deposit of contaminants on the wafer.